BACKGROUND፡ The association of dietary patterns (DPs) linked to the severity of coronary artery disease (CAD) is little known. Therefore, this study aims to explore the relationship between major DPs and the severity of CAD.METHODS: This cross-sectional study was conducted among423 newly discovered CAD patients (both genders, aged 35-65 years), who underwent coronary angiography. The severity of CAD was assessed by the Gensini score. All patients were tested using a semi-quantitative food frequency questionnaire and other related data through face-to-face interviews. Factor analysis and logistic regression were applied by using SPSS version-24.RESULTS: By principal component analysis, two major DPs were identified: “Unhealthy” DP that characterized mainly by high intakes of sugar and sweets, soft drinks, salts, cooking oils, and processed meats, and “Healthy” DP that consisting high intakes of fruits, fish, poultry, vegetables, whole grains. After adjustment for confounding variables, the odds of severe CAD was significantly higher in the third (T3) and second (T2) tertile of the unhealthy pattern by 4.79 and 2.48 times more compared to the first tertile (T1) (OR 4.79; 95%CI 2.60, 8.83; P<0.001) and (OR 2.48; 95%CI 1.40, 4.39; P=0.002), respectively. However, the odds of CAD severity in the T3 and T2 of the healthy pattern was lowered by 0.24 and 0.38 times less compared to the T1 (OR 0.24; 95%CI 0.12, 0.47; P=0.002) and (OR 0.38; 95%CI 0.20, 0.73; P=0.006), respectively.CONCLUSION: The severity of CAD was significantly increased by the unhealthy dietary pattern, while decreased by adherence to the healthy pattern.KEYWORDS: Dietary patterns; Severity of coronary artery disease; Gensini score; Factor analysis, International physical activity questionnaire.